<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <title>数据代理</title>
</head>
<body>
<script>
 /* 通过一个对象代理另一个对象的读写操作 */
 let obj1 = {
   x: 100
 }
 let obj2 = {
   y: 200
 }
 Object.defineProperty(obj2,'x', {
   get() {
     return obj1.x;
   },
   set(value) {
     obj1.x = value; 
   }
 })
</script>
</body>
</html>